1. Field of the Invention
The invention relates to the field of optical coherence tomography and in particular to optical endoscopic scanning probes used with optical coherence tomographic interferometers.
2. Description of the Prior Art
As a noninvasive imaging technique, optical coherence tomography (OCT) provides high resolution morphological, structural, and functional information in biological tissues. Other noninvasive morphological imaging techniques such as X-ray radiography, magnetic resonance imaging (MRI), computed tomography (CT) and ultrasound imaging have been widely used in various clinical applications with resolutions ranging from 100 μm to 1 mm. However, this resolution is insufficient to delineate the microstructure of biological tissues at the level required to detect many abnormalities, such as early cancers. OCT can achieve an ultrahigh resolution as high as 1 μm in real time, in-situ without specimen removal and processing making it highly attractive for clinical imaging. Since it was first introduced in 1991, OCT has been used to identify microstructures in ophthalmology, skin, oral cavity, respiratory tract, gastrointestinal tract, and bladder. In recent reports, OCT endoscopic and catheter based probes have been developed for clinical use.
To image tissues, movable parts such as MEMS mirrors, MEMS micromotors, linear motors, or rotary fiber joints are used to perform two dimensional imaging or circumferential scanning. Since the mirror size and numerical aperture are limited by the endoscope size, the lateral resolution is subsequently restricted. Three dimensional scanning can be accomplished by repeating the scans with an added directional motion component, but this may be technically challenging in small diameter endoscopic probes, particularly when precisely aligning components. In confined spaces of endoscopic probes, the sweep distances obtainable using MEMS probes may also be quite limited.
Optical coherent tomography (OCT) has been used for high resolution optical imaging in many areas of medicine, especially ophthalmology. The “conventional wisdom” was that OCT could not be done through flexible fiber bundles. The use of flexible fiberoptic bundles to deliver OCT directly to a tissue sample has not been previously achieved.